Polaroid cameras using the patented process of Dr Edwin Land, were the first commercially successful instant picture cameras which were easy to use, and were not in need of bottles of chemicals, etc.
The idea of in-camera developmental is not new: there are records of ideas for instant cameras from the first year of photography. In 1857, Bolls and Smith of Cooperstown, New York patented the first instant camera which actually went into production.
Jules Bourdin of France invented a simple system which was successfully marketed as early as 1864. Many other attempts met with mediocre success, but Polaroid caught on and became a household word. Because of the success of the company, their cameras generally are quite common, and obviously none are very old.